Police in Wellingborough have received reports that a few residents have become victims of online fraud.
The scams are believed to involve online trading sites Ebay and Gumtree.
Buyers have been asked to ship sale items to Nigeria and other foreign countries and told that they will be paid once a tracking number proving postage is received. The payment is never received.
Officers are advising people never to post items until payment has been received from the other party.
A second scam involved a phone call from someone claiming to be a police officer, with news that their bank has experienced problems and their money was not safe.
The suggestion is made for them to transfer their funds from the unsafe bank account into a specified account and sort code.
PCSO Rachel Head said: “While crime figures in the area are relatively low, we are aware of a few recent cases of this type of fraud.
“Never share personal information unless you are entirely confident you know who you are dealing with. Be particularly cautious if you are cold-called by someone claiming to be from a bank or from the police.
“If you are at all in doubt, contact your bank or building society immediately and all 101 to report your suspicions.”
To help minimise the risk of becoming a victim by being aware of how to identify online fraudulent transactions, visit www.northants.police.uk/crimeprevention or visit either www.cifas.org.uk or www.identityfraud.org.uk